Ignition device for internal combustion engines

ABSTRACT

Ignition device for an internal combustion engine having a spark gap ignitable by the secondary voltage of a transformer in accordance with mechanically controlled, brief variations in the primary voltage of the transformer includes a magnetic fielddependent resistance connectible to the primary coil of the transformer, permanent magnet means displaceable relative to the resistance, and yoke means comprising a circuit for magnetic flux from the permanent magnet means, the circuit being continuously maintainable irrespective of the displaced position of the permanent magnet means, the resistance being intermittently connectible in the circuit in the course of displacement of the permanent magnet means.

United States Patent Hini [54] IGNITION DEVICE FOR INTERNAL COMBUSTION ENGINES Munich, Germany 22 Filed: 9,1969

[2|] Appl.No.: 883,456

[30] Foreign Application Priority Data Dec. I0, 1968 Germany......................P l8 l3 591.6

[52] U.S.Cl ..l23/l48E, 123/!49 [5|] [/00 [58] FieldoISearch ..|23/l48E [56] References Cited UNITED STATES PATENTS 3,332,406 7/1967 Perry et al. ..l23/l02 3,461,85l 8/1969 Stephens l 23/l48 3,464,397 9/1969 Burson l 23/ l 48 [451 July 11, 1972 Piteo 1 23/148 3,484,677 IZ/ l 969 FOREIGN PATENTS OR APPLICATIONS 958,97l 2/1957 Germany...............................l23/148 Primary Examiner-Laurence M. Goodridge Assistant Examiner-Ronald B. Cox

Attorney-Curt M. Avery, Arthur E. Wilfond, Herbert L. Lerner and Daniel J. Tick ABSTRACT Ignition device for an internal combustion engine having a spark gap ignitable by the secondary voltage of a transformer in accordance with mechanically controlled, brief variations in the primary voltage of the transformer includes a magnetic field-dependent resistance connectible to the primary coil of the transfomier, permanent magnet means displaceable relative to the resistance, and yolte means comprising a circuit for magnetic flux from the permanent magnet means. the circuit being continuously maintainable irrespective of the displaced position of the permanent magnet means, the resistance being intermittently connectible in the circuit in the course of displacement of the pemianent magnet means.

QCIaInmSDnwingIlgures PATENIEDJUL 1 1 1912 2 3 SHAFT ROTARY SPEED CONTROL Fig.3

'sir' Win" '1a'0" 'zllm' ar'lr' LOO- IGNITION DEVICE FOR INTERNAL COMBUSTION ENGINES My invention relates to ignition device for internal combustion engines and more particularly to such ignition device wherein the spark gap is actuated by a secondary voltage produced by a transformer, the primary voltage of the transformer being subjected to mechanically controlled, brief variations. To control the primary voltage, through an amplifier particularly, a magnetic field-dependent resistance is provided with respect to which a permanent magnet, or a pole thereof, is relatively displaceable.

Control of the ignition process is vital for internal combustion engines. In practice, mechanical means are employed almost exclusively for this purpose. These are subjected to very great wear and require frequent replacement.

To reduce the susceptibility of ignition devices to breakdown, so-called transistor or thyristor ignitions have been introduced which, in addition to increasing the ignition power output over that of the previously known aforementioned mechanical ignitions, have also decreased the current load on the breaker contacts and, consequently, the burn-off wear thereof. With such electronic ignition devices, however, there is also a reduction in the breaker current, and a greater uncertainty is thereby produced with respect to the engagement of the breaker contacts. This can cause breakdowns, especially with the thyristor ignitions. Also, the wearing processes resulting from cam control are retained to the fullest extent in the transistor or thyristor ignitions as for those of the heretofore known mechanical ignition devices.

To reduce wear, a socalled lighting current control device is employed, by means of which the breaker or interrupter mechanism of the ignition device can be dispensed with. In such a lighting current control device, for example, a cylinder formed with a slit is rotated between a light source and a photoelectric cell and, as the photocell is periodically irradiated by the light, an ignition device is actuated through a suitable transistor circuit electrically connected to the photocell. Such a device has, however, also proven to be too often susceptible to breakdown, especially when employed in motor-driven vehicles.

An ignition device is known from German Pat. No. 958,971 wherein the ignition process is controlled by a magnetic field dependent resistance, relative to which a permanent magnet is displaceable. The use of magnetic field-dependent resistances, several of which can be installed in a single device, produces a contactless ignition voltage switch or controller.

It is an object of my invention to provide ignition device for internal combustion engines which avoids the aforementioned difficulties of the heretofore known devices of this general type and which, moreover, affords improvement over those devices employing magnetic field-dependent resistances, by eliminating the reactive forces which are produced in the heretofore known devices, due to the repeated interruption or breaking of the magnetic flux during relative motion of the permanent magnet and the resistances.

With the foregoing and other objects in view, I provide, in accordance with my invention, ignition device for an internal combustion engine having a spark gap ignitable by the secondary voltage of a transformer in accordance with mechanically controlled, brief variations in the primary voltage of the transformer comprising a magnetic field-dependent resistance connectable to the primary coil of the transformer, permanent magnet means displaceable relative to the magnetic field-dependent resistance, and yoke means comprising a circuit for magnetic flux from the permanent magnet means, the magnetic flux circuit being continuously maintainable irrespective of the displaced position of the permanent magnet means, the magnetic field-dependent resistance being intermittently connectable in the magnetic flux circuit in the course of displacement of the permanent magnet means.

Consequently, the magnetic flux is not interrupted, and no reactive forces can therefore form. The durability of the ignition device of my invention is accordingly virtually unlimited since mechanical wearing processes are eliminated, and the disadvantages occurring with the heretofore known devices of this general type, especially with respect to contact-making, resonance phenomena and frequency unsteadiness are not applicable to the ignition device of my invention.

In accordance with further features of my invention, the permanent magnet means includes a permanent magnet formed with a central bore within which a rotary shaft of the internal combustion engine is rotatably mounted. The magnetization of the permanent magnet is in a direction parallel to the axis of the rotary shaft. Also provided is a disc formed with teeth equidistantly spaced from one another along the periphery thereof, the disc being fastened to the rotary shaft so as to be rotatable therewith and being engageable with a face of the permanent magnet.

in accordance with additional features of my invention, the yoke means is located at one side of the permanent magnet opposite the side thereof engageable by the toothed disc. The yoke means includes three cross-pieces extending parallel to the axis of the rotary shah and having respective ends that are nearly flush with the teeth of the rotatable disc. The magnetic field-dependent resistance is mounted at the middle crosspiece. The mutual spacing of the cross-pieces and the length thereof along the periphery of the disc are predetermined so that in the course of rotation of the disc, a continuous magnetic flux circuit exists either through two teeth of the disc and both outer cross-pieces or between one tooth of the disc and the middle cross-piece. This embodiment affords the particular advantage that the magnetic flux remains nearly constant during the course of rotation of the toothed disc, and the entire magnetic flux passes through the magnetic field-dependent resistance when the latter is connected in the circuit, resulting in a large change in resistance.

in accordance with further features of the invention, the middle cross-piece is replaceably mounted in the yoke means and is exchangeable in the event of the occurrence of a disruption in operation due to failure of the magnetic fleld-dependent resistance. In addition, the magnetic field-dependent resistance is well protected against damage and soiling.

in accordance with other features of my invention in another embodiment thereof, the yoke means located at the side of the permanent magnet opposite that at which the permanent magnet is engaged by the disc is provided with an annular ring disposed coaxially to the rotary shaft and having respective ends that are nearly flush with the teeth of the rotatable disc, the magnetic field-dependent resistance being disposed in an air space located between the disc teeth and the annular ring.

In accordance with a concomitant feature of my invention, the magnetic field-dependent resistance is formed of semiconductive crystalline indium antimonide (lnSb), especially with inclusion in the crystalline structure thereof of a second crystalline phase, such as nickel antimonide (NiSb), for example, having relatively good conductivity.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in ignition device for internal combustion engines, it is nevertheiess not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIGS. 1 and 2 are sectional and plan views, respectively, of one embodiment of the ignition device for internal combustion engines according to my invention, the sectional view of FIG. 1 being taken along the line l[ in FIG. 2;

FIG. 3 is a plot diagram of resistance to angular rotation of the magnet means for a given width of air gap between the magnet means and cross pieces of the yoke of my device; and

FIG. 4 and 5 are sectional and plan views, respectively, of another embodiment of the ignition device of my invention, the sectional view of FIG. 4 being taken along the line IV-IV in FIG. 5, which shows the device with the cover thereof removed.

Referring now to the drawing and first, particularly, to FIG. 1 thereof, there is shown in cross section, the ignition device of my invention which includes a distributor shaft 1, driven by the internal combustion engine and rotatably mounted in a central bore 2 formed in an annular permanent magnet 3 such as an oxide magnet, for example. The magnetization of the permanent magnet 3 is parallel to the longitudinal axis of the shaft so that, as indicated in FIG. 1, the north pole N of the permanent magnet 3 is in the upper half thereof whereas the south pole S is in the lower half thereof. An iron circular disc 5 is fastened by a screw 4 to the shaft I, and is formed with teeth I5 (FIG. 2) spaced equidistantly along the periphery thereof. The disc 5 is disposed on the upper surface of the permanent magnet 3, as viewed in FIG. 1, and the teeth 15 thereof form rotary poles of the permanent magnet 3 which remains stationary. It should be noted, however, that the permanent magnet 3 can also be fastened to the disc 5 so as to be rotated therewith by the distributor shaft 1.

An iron plate 6, as shown in FIG. 1, is fastened to the undersurface of the permanent magnet 3 and is, in addition, connected through spacers 7 to a support plate 8. Of course, if the permanent magnet 3 were fastened to the disc 5 so as to be rotatable therewith by the distributor shaft 1, it would then not have the iron plate 6 fastened to the undersurface thereof. Three crosspieces 9 to II of iron are disposed at a marginal portion of the iron plate 6. The middle cross-piece I is shown in FIG. I. The cross-pieces 9 to II extend parallel to the Iongitudinal axis of the shaft I and are respectively formed with a radially inwardly directed projection which has an inner surface virtually flush with the periphery of the toothed annular disc 5. Thus, only a very narrow air gap 11 is formed between the teeth I of the disc 5 and the projections of the crosspieces 9 to II at corresponding rotary positions of the disc 5, and the plate 6, together with the cross-pieces 9 to 11 form a yoke which completes the circuit of the magnetic field of the permanent magnet 3 passing through the pole-like annular disc 5.

As can be seen in FIG. 1, a disc-like magnet field-dependent resistance 13 is disposed in the middle cross-piece so that the magnetic flux passing through the cross-piece I0 traverses the resistance 13 in a direction perpendicular to the lateral surfaces thereof. The magnetic field-dependent resistance I3 is thus protected against disturbance and soiling. In addition, the middle cross-piece 10 can be relatively easily exchanged by loosening the screw I4 with which it is fastened to the iron plate 6. Breakdowns in operation are therefore able to be simply and inexpensively eliminated The electric terminals for the magnetic field-dependent resistance I3 are not shown in FIG. I in the interest of clarity.

In the plan view of FIG. 2, the equally spaced distribution of the teeth 15 about the periphery of the annular disc 5 is clearly shown. The number of teeth (six in FIG. 2) corresponds for example to the number of cylinders in the internal combustion engine with which it is used. The teeth 15 are located momentarily opposite the projections of the cross-pieces 9 to II as the disc 5 is rotated. The magnitude of the magnetic flux is adjustable by suitably selecting the area covered by the teeth 15 and the width of the air gap 12. The width of the cross-pieces 9 and II in the peripheral direction of the disc 5 and and mutual spacing of the cross-pieces 9 to ll are such that in the course of rotation of the disc 5, the magnetic flux of the pennanent magnet 3 passes through a circuit containing two teeth 15 and the outer cross-pieces 9 and II respectively as well as the iron plate 6 or through a circuit containing one tooth 15, the middle cross-piece I0 and the iron plate 6, there always being a completely closed circuit of the magnetic flux. By means of this construction, in the course of rotation of the disc 5, the magnetic flux always remains nearly constant since the flow thereof from the permanent magnet is transferred to either the two outer cross-pieces 9 and II, on the one hand, or to the middle cross-piece 10, on the other hand. The magnetic fielddependent resistance 13 is disposed in the return flow path of the magnetic flux through the middle cross pieces ID. The entire magnetic flux flows through this middle cross-piece I0 in the positiOn of the disc 5 illustrated in FIG. 2, an optimal variation in resistance of the magnetic field-dependent resistance 13 being thereby attained. In the intermediate positions i.e. when for example the tooth shown opposite the middle cross-piece I0 in FIG. 2 is located opposite the respective outer cross-pieces 9 and 11. the magnetic flux is transferred to both outer cross-pieces 9 and II. This has the advantage that stray or scattered flux of the magnet does not markedly affect the basic resistance of the field plate 6.

In FIG. 3 there is shown by plot diagram, a periodic change in resistance for an air gap 12 having a width of 0.15 mm. In the plot diagram of FIG. 5, the resistance R is given in ohms along the ordinate while the rotary angle in degrees for the disc 5 over one rotation thereof is given along the abscissa. With the aid of the variation in resistance as illustrated, the primary voltage of the transformer for the spark gap is able to be periodically controlled. The temperature dependence i.e. the temperature variation for the change in resistance in the range of from -60 to +l00 C. is relatively small and the change in resistance is independent of the rotary speed of the shaft 1. The rotary speed of the shaft 1 and consequently of the motor can therefore be determined from the electric signal derived with the magnetic field-dependent resistance 13. The measurement of the rotary speed can be effected simultaneously with the control of the ignition process.

A further example of the change ignition device of my invention is shown in the cross sectional view of FIG. 4. In the embodiment of FIG. 4, instead of a yoke formed of three cross-pieces and the iron plate 6, the yoke 16 is constructed in the form of a pot in the embodiment of FIG. 4 and is fastened to the permanent magnet 3 by any suitable means. The side wall of the pot-shaped yoke 16 is provided with an annular projection 17 extending radially inwardly from the wall of the pot-shaped yoke 16 toward the shaft 11 and is flush with the teeth 15 of the disc 5. Due to the fact that this projection 17 is a closed ring, the magnetic flux is not interrupted in the course of rotation of the disc 5 and no reactive forces can be produced.

The magnetic field-dependent resistance I3 is disposed at any desirable location in the air space 12 located between the toothed zones 15 of the disc 5 and the ring-shaped projection 17. The magnitude of the magnetic flux is adjustable in accordance with the area of the teeth I5 and the width of the air gap 12 between the surface of the teeth and the radially inward circular projection 17. The magnetic field-dependent resistance 13 is traversed by magnetic flux whenever a tooth I5 of the rotary disc 5 sweeps past the field-dependent resistance 13. The attainable periodic changes in resistance resulting therefrom are analogous to those illustrated in the pot diagram of FIG. 3.

A cover I8 is provided on the ignition device of FIG. 4 for shielding the magnetic field and also for protecting the device against soiling. FIG. 5 is a plan view of FIG. 4 with the cover 18 removed. In FIG. 5 there is shown a stage of the rotation of the disc 5 wherein the magnetic field-dependent resistance 13 is located in the air gap 12 between one of the teeth 15 and the ring-shaped projection I7. Ignition devices of exceptional operational reliability can be constructed in accordance with the aforedescribed device of my invention. Their manufacture requires no special economic outlay, and the ignition device of my invention can be installed in the housings of conventional mechanical breakers or interrupters without requiring any special alteration.

Iclaim:

l. Ignition device for an internal combustion engine having a spark gap ignitable by the secondary voltage of a transformer in accordance with mechanically controlled, brief variations in the primary voltage of the transformer comprising a magnetic field-dependent resistance connectable to the primary coil of the transformer, permanent magnet means displaceable relative to said magnetic field-dependent resistance. said permanent magnet means having a pair of magnet poles and a plurality of pole shoes for one of said poles, and yoke means connected to the other of said magnet poles and comprising a circuit for magnetic flux from said permanent magnet means, said circuit being continuously maintainable for cnducting a substantially constant magnetic flux in the same flow direction therethrough irrespective of the displaced position of said permanent magnet means, said magnetic field-dependent resistance being intermittently connectable in said magnetic flux circuit in the course of displacement of said permanent magnet means.

2. Ignition device according to claim I wherein said permanent magnet means comprises a permanent magnet and a disc engageable with a face of said permanent magnet, said permanent magnet being formed with a central bore within which a shaft rotatable by the internal combustion engine is mounted, said permanent magnet having magnetization extending in direction parallel to the axis of said rotary shaft, said disc being fastened to said rotary shaft so as to be rotatable therewith, said pole shoes being located equidistantly spaced from one another along the periphery of said disc.

3. Ignition device according to claim 2 wherein said yoke means is located in part at a side of said permanent magnet opposite said face thereof with which said disc is engageable and comprises three cross-pieces extending parallel to the axis of said rotary shaft and located along the periphery of said disc, said crosspieces having end faces disposed so as to be nearly flush with said pole shoes of said rotary disc, said cross-pieces having predetermined mutual spacing and respective lengths along said periphery of said rotary disc for forming, in the course of rotation of said disc, continuous magnetic flux circuit means alternately through two pole shoes of said disc and both outer cross-pieces, on the one hand, and between one pole shoe of said disc and the middle cross-piece, on the other hand, said magnetic-field dependent resistance being connected in said middle cross-piece.

4. Ignition device according to claim 3 wherein said middle cross-piece is removable and replaceable.

5. Ignition device according to claim 2 wherein said yoke means is located in part adjacent a face of said permanent magnet opposite said face thereof with which said disc is engageable and comprises an annular ring disposed coaxially to said rotary shaft and having an end face nearly flush with said pole shoes of said rotary disc, said magnetic field-dependent resistance being disposed in an air space located between said annular ring and said disc teeth.

6. Ignition device according to claim 1 wherein said magnetic field-dependent resistance is formed of semiconductive crystalline indium antimonide.

7. Ignition device according to claim 6 wherein said semiconductive crystalline indium antimonide has inclusions of a second crystalline phase possessing relatively good conductivity.

8. Ignition device according to claim 2 including means for determining the rotary speed of said rotary shaft in accordance with an electrical signal from said magnetic field-dependent resistance.

9. Ignition device for an internal combustion engine having a spark gap ignitable by the secondary voltage of a transformer in accordance with mechanically controlled, brief variations in the primary voltage of the transformer comprising a magnetic field-dependent resistance formed of semiconductive crystalline indium antimonide having inclusions of a second crystalline phase formed of nickel antimonide and being connectible to the primary coil of the transformer, permanent magnet means displaceable relative to said magnetic field-dependent resistance, and yoke means comprising a circuit for magnetic flux from said permanent magnet means, said circuit being continuously maintainable irrespective of the displaced position of said permanent magnetmeans, said magnetic field-dependent resistance being intermittently connectible in said magnetic flux circuit in the course of displacement of said permanent magnet means.

i l I I! 

1. Ignition device for an internal combustion engine having a spark gap ignitable by the secondary voltage of a transformer in accordance with mechanically controlled, brief variations in the primary voltage of the transformer comprising a magnetic fielddependent resistance connectable to the primary coil of the transformer, permanent magnet means displaceable relative to said magnetic field-dependent resistance, said permanent magnet means having a pair of magnet poles and a plurality of pole shoes for one of said poles, and yoke means connected to the other of said magnet poles and comprising a circuit for magnetic flux from said permanent magnet means, said circuit being continuously maintainable for conducting a substantially constant magnetic flux in the same flow direction therethrough irrespective of the displaced position of said permanent magnet means, said magnetic field-dependent resistance being intermittently connectable in said magnetic flux circuit in the course of displacement of said permanent magnet means.
 2. Ignition device according to claim 1 wherein said permanent magnet means comprises a permanent magnet and a disc engageable with a face of said permanent magnet, said permanent magnet being formed with a central bore within which a shaft rotatable by the internal combustion engine is mounted, said permanent magnet having magnetization extending in direction parallel to the axis of said rotary shaft, said disc being fastened to said rotary shaft so as to be rotatable therewith, said pole shoes being located equidistantly spaced from one another along the periphery of said disc.
 3. Ignition device according to claim 2 wherein said yoke means is located in part at a side of said permanent magnet opposite said face thereof with which said disc is engageable and comprises three cross-pieces extending parallel to the axis of said rotary shaft and located along the periphery of said disc, said cross-pieces having end faces disposed so as to be nearly flush with said pole shoes of said rotary disc, said cross-pieces having predetermined mutual spacing and respective lengths along said periphery of said rotary disc for forming, in the course of rotation of said disc, continuous magnetic flux circuit means alternately through two pole shoes of said disc and both outer cross-pieces, on the one hand, and between one pole shoe of said disc and the middle cross-piece, on the other hand, said magnetic-field dependent resistance being connected in said middle cross-piece.
 4. Ignition device according to claim 3 wherein said middle cross-piece is removable and replaceable.
 5. Ignition device according to claim 2 wherein said yoke means is located in part adjacent a face of said permanent magnet opposite said face thereof with which said disc is engageable and comprises an annular ring disposed coaxially to said rotary shaft and having an end face nearly flush with said pole shoes of said rotary disc, said magnetic field-dependent resistance being disposed in an air space located between said annular ring and said disc teeth.
 6. Ignition device according to claim 1 wherein said magnetic field-dependent resistance is formed of semiconductive crystalline indium antimonide.
 7. Ignition device according to claim 6 wherein said semiconductive crystalline indium antimonide has inclusions of a second crystalline phase possessing relatively good conductivity.
 8. Ignition device according to claim 2 including means for determining the rotary speed of said rotary shaft in accordance with an electrical signal from said magnetic field-dependent resistance.
 9. Ignition device for an internal combustion engine having a spark gap ignitable by the secondary voltage of a transformer in accordance with mechanically controlled, brief variations in the primary voltage of the transformer comprising a magnetic field-dependent resistance formed of semiconductive crystalline indium antimonide having inclusions of a second crystalline phase formed of nickel antimonide and being connectible to the primary coil of the transformer, permanent magnet means displaceable relative to said magnetic field-dependent resistance, and yoke means comprising a circuit for magnetic flux from said permanent magnet means, said circuit being continuously maintainable irrespective of the displaced position of said permanent magnet means, said magnetic field-dependent resistance being intermittently connectible in said magnetic flux circuit in the course of displacement of said permanent magnet means. 